a)Where Ridley had been going
Ridley Scott had been experimenting with the idea of an egg silo inspired by the Castle Harkonnen,
and had been exploring the idea of a giant rocket capsule shaped derelict ship with Moebius before he left. (see:Moebius derelict exterior and Ridley Scotts Early Egg Silo Exterior )

b)What Giger drew
HR Giger designed a breast shaped building called the Egg Silo, a hundred and fifty metres tall and two hundred metres in diameter. He drew the images in April of 1978. Perhaps he borrowed the shape from Ridley's early idea for a derelict ship that he work on with Moebius. It also included ideas from Giger's painting Dune I which showed an
entrance to the Castle Harkonnen.

Egg Silo exterior (uploaded by me, taken from Giger's Alien)

Egg Silo exterior (uploaded by me, taken from Giger's Alien)

Egg Silo exterior (uploaded by me, taken from Giger's Alien)

Giger's Dune I (Entrance to Castle Harkonnen), 1976

Ridleygram of explorer climbing up the side of the egg silo

c)Giger's Painting
In the painting, in the rock formations, suggestions of
perhaps long fossilized life forms. Perhaps the rock sticking out of
the lower ground to the left of the building is a half formed impression
of Cthulhu type entity with its tentacled face and thick claw. Giger had brought his designs at the time over to Shepperton for approval on March 30th of 1978, although they were met with general approval, he is told that his egg silo would be too expensive to build.

Quote source

HR Giger: The designs I brought with me meet general approval. The eggsilo (plate 378) can't be built because it would be too expensive. Pity! (Giger's Alien, p14)

378: Egg Silo exterior (uploaded by me, taken from Giger's Alien)

d) Kenner Alien Logo

The design of this structure would be used in the logo for the Kenner Alien toys that would soon be sold.

a) Reaching the first version
By 19th July, 1978, Giger's concept for an Egg Silo interior had evolved. This became version 1.
The
egg wagons that had scooped up the eggs and transported them along a
rail to the pipes had disappeared, along with their monorails, they had now been
transformed into big pregnant capsules on the wall of the silo which
Giger had decided were symbols of fertility. Above the capsules were entrance tubes coming down at the side rather than in the centre of a circular buildings, and a space for the hieroglyphics painting to be seen. (see also : Placement of Life Cycle Tableau )

Work 386 Egg Silo version I

b) Echoes of Foss
After comparing Chris Foss' elongated derelict ship and Giger's Egg Silo version I painting, it might be easy to assume that Giger had taken the general form of Foss' derelict as a starting point for the painting, and now the two slit windows on the pod from Foss' derelict that had translated themselves into a slightly different form in one of Moebius' earlier derelict designs has almost seem to crawl into Egg Silo version 1 as two slit like eye like spaces above the pod, or maybe such abstract bilateral forms protruding from the tops of various of Foss' structures that might be such things as engines or something similar to two rectangular radars fused together that might make one think of robot eyes or visors ( See Chris Foss' Alien temple interior and Chris Foss' derelict,
and Moebius Alien spaceship concepts part 2)

Front pod from a derelict ship by Chris Foss'

front pod from Moebius derelict with eye like
spaces at the front inspired by Foss' derelict

HRGiger:19th July 1978, Shepperton Studios. Luckily the wretched idea of only having six eggs has been dropped. Scott somehow managed to persuade O'Bannon, or else he's simply acted on his own authority. The victory is followed by another defeat. During my absence someone has attacked me in the rear and had decided to do away with the big "pregnant" capsules (plate 386), the symbol of fertility in this set. The reason: ' They're superfluous." Superfluous? When Voysey, who has to be working in five places at once, has prepared a scale mdoel in meticulous detail (plates 386d and e)? I suppose I shall never master the secret of how such decisions are taken. It is getting clear to me that my creative capacity is slowly but surely being numbed. I'm still convinced that the best critic of an artist's work is the artist himself. (Giger's Alien, p44)

drawing with another variable for the egg silo interior
with pregnant capsule to the side of the entrance shafts
from Giger's Alien Diaries

sketch from Giger's Alien

sketch from Giger's Alien

sketch from Giger's Alien

from Giger's Alien Diaries

c) Voysey creates miniature
Peter Voysey had been busy created a 1/25th scale model of
the silo interior, however despite his work on this, in Giger's absence the pregnant capsules were
declared superfluous and the entrance tubes disappeared as well

"Original Chris Foss concept sketch of the
Derelict Ship interior for
Alien. The image
depicts a member of the Nostromo landing
party
descending into a vast and ornate
sepulcher. The sketch shows Foss’
celebrated
skill while markedly devoid of the later influence
of H.R.
Giger. Accomplished in pencil, ink and
gouache on 29 x 18 in. artist leaf. Handwritten
notations “Centre of the Tombe”, “Alien” and
“Chris
Foss F 77” at the lower border. Verso
features a sticker in the upper
left reading
“Chris Foss – 7. Centre of the Tombe”. "
(http://www.sciencefictionarchives.com/)

a) The vast temple interior created by Chris Foss had the look of something that was created for giants. The explorer lowers himself from the shaft above above a plinth that might be as large as a three or four story building and perhaps it looks as if it could easily be an oven with a kitchen chimney above it.

Chris Foss pyramid birth temple interior (this copy of the image was taken from http://io9.com/)

b) Vast shaft entrances on the side of the plinth might be the air intakes of huge long engines for airborne craft , the left might secretly be a representation of a strange creature with wide open maws and eyes on top of stalks that seem like siamese twin versions of military ships radar antennae. and long fins or wings sticking out of the back.

a)Segmented Circular ContainerDrawn on the 19th April 1978, early in the production, HR Giger's first drawing for the egg silo, was a circular container, divided into segments of equal size by rods running from the top of the wall to the mid-point of the floor, and each segment was filled with eggs

Egg Wagons (2)

b)Entrance TubeAn entrance tube made from a membrane hangs down from the ceiling, with tubes down the the side. Perhaps an egg is seen to fall from the central tube in the first picture.

c)Egg Wagons
Little egg wagons with scooper like devices run along a monorail made from the dividing rods and up to the ceiling along the partitions
in the building.The wagon swivels around, and a tongue like device extends from it, picking up the eggs and holds its within a container before running up along the wall and up along the arch of the ceiling to deposit it in an opening at the top of an egg tube.

Source quote

HR Giger: The interior of the eggsilo which now forms a circular container, is divided into segments of equal size by rods running from the top of the wall to the mid-point of the floor, each segment is filled with eggs. (Giger's Alien, 6th July 1978, p42)

a) Questions about nudityOriginally, in the scene where the crew rise from their cryotubes, everyone was naked, and one of the things that Sigourney thought was very interesting about the film, coming from her theatre background, without thinking about the markets, the Catholics, ratings and censorshop, was this very striking idea about pink vulnerable creatures moving through a very hard metallic environment, it offered a nice contract and this was not shot because Fox said " We'll lose Spain and we'll lose Italy, so
you have to wear cloths". But still there was this idea of filling as much flesh as possible within the environment to show what a human being was, in space. Sigourney did realise it was erotic but it was something very important.

Ripley stripping off in Alien

Ripley stripping off in Alien

Ripley stripping off in Alien

Ripley stripping off in Alien

b) The StripSo the other side of the fourth act is the fact that Ridley stripped the Ripley character down,
Sigourney Weaver in the part is strong, capable and attractive and he
wanted to increase the sense of her peril by showing her undressed,
Ripley does a modest strip down to her underwear. It not only made this
ballsy sort of lady vulnerable - but sexy too. Sigourney's understanding about the intentions behind the strip was that it wasn't about sex, not for her or for Ridley either, and Ripley obviously didn't want to go into hypersleep
covered in blood and god know what else, she just wants to take her
clothes off and have a bath, also she is relaxing, thinks it's over, goes about her business and suddenly the worst possible thing happens, she's not prepared and is vulnerable as can be.Later she would have people say to her ‘Aw, how could you demean yourself by doing a striptease?’ And she would respond ‘Are you kidding? After five days of blood and guts, and
fear, and sweat and urine, do you think Ripley wouldn’t take off her
clothes?’"It never occurred to her for a second that people would think that her strip was exploitative. However she thought it was provocative

Sigourney in her underwear between takes

Sigourney in her underwear between takes

c) Possibilities of the alien's sensuous nature Ridley
appeared to Sigourney to have thought that there were great erotic
possibilities for the scene in which the alien comes out of its hiding place to watch Ripley in the closet as she's shedding her clothes, perhaps as if she was a snake shedding its skin or just another creature suddenly removing its shell, so that it looked as if she was going from a dark green and crusty looking animal in her clothes to a pink and white, soft animal.

Because it saw skin, the alien would not attack because it was being drawn to her, finding what she was doing amazing and it would be moved or emotionally touched in some way, perhaps with sexual fascination, and because she was so different to itself. She was thinking along the lines of the idea of beauty and the beast.

So she discussed on the set the possibility of this creature watching
Ripley with voyeuristic passion, but on the other hand Sigourney knew that the Alien was
resting. As an actress she remained inspired to think about the alien’s
sensual side, (and found in the later Alien sequel, Alien Resurrection, eighteen years later a way to experience a kind of a
sexual interaction with the alien creature in one of its manifestations.)Ridley and Sigourney had also discussed an ending where she is still dressed and is surprised by the alien, so she would run into the closet, take one suit off and put another one on and there would be the moment where the Alien would see her in between suits and be fascinated, because the Alien wasn't evil, it just followed its natural instincts to reproduce through whatever living things were around it.After the movie, every now and then a reporter would ask "How
could you have been part of a film about such evil?"And Sigourney would respond ‘Good Lord! You take this very seriously, don’t you?’

the alien's jaw tongue

d) Further questions about Sigourney's point of view From Ridley's point of view, he only tended to talk about an interest in the erotic
possibilities of Ripley shedding her clothes rather than have a point about what the Alien was thinking in a sensuous way. He further looked at Sigourney Weaver's idea some years later in hindsight, and thought that
perhaps she has a touch of sympathy for the creatures because she looks
at it from the viewpoint of her character. Ripley was part crew member
and part scientist, someone who thought in logical terms. And maybe at
that moment, her scientist side emerged and she began to study the
creature like a scientist would and started to get a perspective on what
it may have been thinking and previous to this scene, one should remember that there
had been
absolutely no communication between the alien and the crew members,
other than violent experiences, but Sigourney was aware that they always wanted an erotic undercurrent in the film, where the audience might ask "What would it do to her?"

Ripley climbing into her space suit

Ripley climbing into her space suit

e) Questions about nudity Sigourney
felt that since the creature had been naked all the way through the
movie, she at least ought to find herself completely naked before this creature at
the end of it all, but this didn’t go down well with the studio bosses
concerns about selling the film to Catholic countries, so she went ahead and wore her underwear which she thought was a cop out. However, she felt that seeing what kind
of response she was going to have from the audience, she thinks it was
just as well she had some clothes on as since then she would think twice about taking off all her clothes in a movie and scampering around for an hour.

Sigourney posing in her helmet

f) Smallest Pair of KnickersThey were looking for a pair of knickers of Sigourney to wear back on the set, they held the shoot up by a couple of hours, the first pair that the costume designers came back with looked to Ridley like a pair of diapers, he wanted something very sex and so he went himself to find something and whatever the smallest pair were, those he came back with. Sigourney was a tall healthy woman with long legs who did a lot of running. Ivor Powell was impressed by how sexy they made her look. However Sigourney wasn't thinking about this being the scene where she shows her underwear, she was trying to present the most utilitarian knickers she could find.

Sigourney posing in her white suit

g) White Knight vs Futuristic Dragon The last twenty minutes
are treated in a very lyrical style, Scott sees this as a reflection of
the way he looks at reality. Ripley is happy to find a space suit and puts it on. so she can get on with what she needs to do. It was more than whether Ripley will
triumph, it becomes a situation with an undercurrent of sexuality where she dons the virginal white space suit and she takes up a fight with a
futuristic dragon. (see also: The alien as a dragon)

expelling the alien from the Narcissus

Source Quotes

Danny Peary: Was there discussion over your famous strip toward the end of the film?Sigourney Weaver:Originally there was going to be a lot of nudity in
the film. Of the matter-of-fact variety. There were going to be lots of
shots of naked people walking around, which I thought was a good idea because it was such a harsh
environment. It would have been a nice contrast. As for my strip… people
have said, "Aw, how could you demean yourself by doing a striptease?"
And I say, "Are you kidding? After five days of blood and guts, and
fear, and sweat and urine, do you think Ripley wouldn’t take off her
clothes?" It never occurred to me for a second that people would think my
strip exploitive. I think it’s kind of provocative – you’re almost
seeing me through the Alien’s eyes. Suddenly I go from dark green animal
to a pink and white animal. Ridley and I had so much fun working out the ending. There were so
many different endings. One of them was that the alien would surprise me
and I would run into the closet where I’d take off my suit and put on
another. So there would've been a moment when the alien would see me
between suits and be fascinated. Because the alien isn’t evil. It’s just
following its natural instincts to reproduce through whatever living
things are around it. Every now and then a reporter would ask, ‘How
could you have been part of a film about such evil?’ And I’d go, "Good Lord! You take this very seriously, don’t you?" So I liked all this stuff. You see the Alien in its birthday suit the
entire film; so I thought it was a cop out having me wear the
underwear, and not stripping entirely. Fox is always concerned about
losing Spain, losing Italy, etc. But I must say, having received the mail I
have, I would now think twice about taking off all my clothes in a movie
and scampering around for an hour.(Omni screen flights/screen fantasy,, Playing Ripley In Alien p162)

Sigourney Weaver:Ridley
thought there were great erotic possibilities for that scene which the
alien, watching Ripley go from green and crusty-looking to something
pink and soft, would find amazing. But face it, if you were in that
situation would you want to go into hypersleep covered and in blood and
god knows what? She just wants to take off what she’s wearing and have a
bath(Photoplay - v30 n12 December 1979)

Ridley : Ripley does a modest strip once in the shuttle, but we kept that to
stress the vulnerability of a lady who’s pretty much a ballsy sort (Ridley Scott interview by David Lewin, Daily Mail 1/10/79)

Ridley Scott:Sigourney has a touch of sympathy for the creature because she looks at
it from the viewpoint of her character. Ripley was part crew member and
part scientist, someone who thought in logical terms. Maybe at that
moment, her scientist side emerged and she began to study the creature
like a scientist would and started to get a perspective on what it may
have been thinking. Previous to this scene, remember, there had been
absolutely no communication between the alien and the crew members,
other than violent experiences.(Omni: ScreenFlights / Screen Fantasies)

InterviewerThe Last Twenty Minutes are treated in a very lyrical style.Ridley Scott: This
is how I like to look at reality. It's not simply a question of knowing
whether or not Ripley will triumph. I wanted to introduce another
dimension. She takes up the fight against some futuristic dragon -
that's why I made her put on the white spacesuit. At the same time, this
has something carnal. She is possessed by the idea of this
confrontation and her behaviour changes completely. (Films Illustrated, vol. 9 no. 99 , "Duelling with Death")

Ivor Powell: I mean, I remember Ridley, 'cause again, this is with his , like
commercial hat on, before we shot that sequence, we like held up
shooting for a couple of hours where I set out one of the costume
designers to go, 'cause the first pair of knickers that they turned up
with for Sigourney to wear, as far as Ridley was concerned looked like a
pair of diapers and they weren't sexy enough, so we all waited while he
went out and came back, and whatever the smallest pair were, those were
the ones that got chosen as you can see etc, I mean, Sigourney's a ,
you know was a very healthy girl, and big sort of legs, she did a lot of
running, etc, but they made her look amazing, sexy, and the whole thing
was this undercurrent of sexuality and that end sequence of her
changing into that virginal white space suit, and then now the alienWayne Imms: yeah, yeah, absolutelyIvor Powell: All of that, talk about Freudian. It was beauty and the beast really., so.(Alien Q &A, Genesis Cinema, August 23rd 2014)

Sigourney Weaver : Originally, in the movie, everyone was naked, and one of the things I thought was very interesting about the film, because, again, I was coming from theater, I wasn't thinking about markets and Catholics and ratings and censorship, was it was so striking to think of these pink creatures, very vulnerable creatures, moving through this very harsh, metallic environment. That was in the script at the beginning. We didn't shoot it that way because Fox said "We'll lose Spain and we'll lose Italy, so you have to wear[clothes]." There was still this idea of filling as much flesh as possible within the environment to show what a human being was, in space. I think it was erotic but that was something I thought was terribly important. Not the girl strips down, but the girl relaxes, thinks it's over, goes about her business and suddenly the worst possible thing happens and she's not prepared, she's as vulnerable as she can be. And happily she finds this space suit and puts it on, so she can get on with it. But it was not about sex to me, and I think, to Ridley. Although, again, we always wanted an erotic undercurrent in the film, because [you'd think] 'what would he do to her?' So that was the genesis of the idea. I was all for it. I didn't even think 'this is a scene where I show my underwear.' I was trying to show the most utilitarian underwear I could find." (Alien The Archive, p96)

Fantastic Films: How did you feel about the scene on the shuttle
where Ripley doffs her clothes not knowing the alien is on boardSigourney
Weaver:What could be more natural that to take off sweaty things I was
wearing, like a snake shedding its skin. Actually there was some nudity
in the script in the beginning of the movie. When we all wake up, we're
supposed to be naked. It was a very provocative visual concept to see
these people moving through such a harsh environment in just their
natural state. But that was changed later.(Fantastic Films #11:, p35)

Ridley Scott: Ripley does a modest strip once in the shuttle, but we kept that in to stress the vulnerability of a lady who's pretty much a ballsy sort.(Cinefantastique, vol 9, no.1)

Questar: There is unusual sexual bias presented in Alien.

Sigourney
Weaver: I think the creature is very sensuous, Ridley always referred
to the alien as "he". At one point when we were discussing the scene at
the end where Ripley is shedding her clothes, there was an idea that
came up which relates to this sexual fascination - but we discussed the
possibility of this creature watching Ripley with a voyeuristic passion.
The alien would not attack because it was fascinated by the fact it
suddenly saw skin. To see another creature without its shell would move it, touch it in some way. We talked about things like that (Questar magazine #5, November 1979)

Sigourney weaver: I think there was [a romantic element] from the very first. The alien coming out of its hiding place and seeing this pink creature
in the closet. Ridley really wanted to go in that direction –
that it was drawn to me because I was so different to it. Sort of beauty
and the beast, I suppose. That was such a strong image to me at the
time, it is so sexual; I've never been able to forget it.(http://www.theguardian.com/film/2014/jul/25/sigourney-weaver-fifth-instalment-alien-saga)

a) This is not where the story ends
The film
was meant to be over when she goes inside the escape shuttle, takes off,
signs off and even with the big bang behind her, that was sound and
mixing between three cards and a wobbly camera and he was supposed to
sign off there. Ridley felt he simply couldn't end the film here "No way, you can't do that, you canna possibly end there"

b) O'Bannon's original ending
Originally Dan O'Bannon had included an ending in the script where the alien was going to be blown out of the Narcissus with Ripley trailing after it. Ridley felt that it was an outrageous ending but he thought it was wonderful. He thought it had to happen but only if it could be done believably real, in a way that it was so outrageous that it would make you want to cheer and clap

c) Ridley's plan
So the actual end of the movie almost never got made, and there are a few stories
about what would have been there right at the end. But Ridley's thoughts went with reintroducing as much of O'Bannon's ending as possible in a way where Ridley would close the lid on the story and then let it out again
so that when Ripley goes into that shuttle, there's a moment when the audience
knows that the film isn't over when you're sitting in the seat.

d) Fourth Act filmed in Four days
He told the the studio bosses "I wanna spend X to give you a fourth act."

They replied "How much?

He added "it'll take us four days"...

They replied "Four Days!"

Ridley responded"you really don't even know what I'm going to do yet,let me explain to you what I'm going to do, then you'll go "how can you do that in four days?" as opposed to "four days!"We're not finishing the film when she jumps in the shuttle, there's a fourth act,"

They said "what do you mean, the film's over when she jumps in the shuttle and takes off and bingo!"

But Ridley's next response was "no, there's a fourth act in there that will change the way films are made"

Fantastic Film: The original ending was different. Can you explain it for us?Ridley Scott:The alien was going to be blown out the door of the Narcissus with
Ripley trailing after it. It was an outrageous ending, but I thought it
was wonderful. I thought it had to happen, but only if it could be
believably done that it would be real. It had to become so openly
outrageous that it wouldmake you want to cheer or clap(interview from Fantastic Films as Reproduced in "Ridley Scott: interviews")

(1:38: 19 /1:41:50) Ridley Scott:Now
the film was meant to be over when she goes inside, ah, you take off,
you do the signing off. Now clearly you can not end the film (1:42:00)here,
even with a big bang behind her. And you know, the big bang's then are
not the big bangs we could do today, but you know what, today it'd be
CGI, this is all real inside the... inside the studio on the set which
is you know, only firewood. Okay so this is all design as the end of the
movie. So there's a one megaton thing going to go off in a second, and
graphic design, interesting uh. Just a flat card , nothing happening, (01:39:00)it's just the sound and mixing between three cards, and I figure
you've got to have two or three, but this, I've go... I've got the
wobbling down now pretty good. Nobody's really wobbled the camera 'til this moment you know I remember til that, so I'm literally wobbling the camera. Bit unsure about the red ball.(1:43:00) And score. Now, this would be the end of the film. But that.. that's it, you would do a signing off there, and I had to say "no way, you can't do that, you canna possibly end there"

Here we made it for 8.6, which even in those days was cheap

(1:39:41 / 1:43:30)SigourneyWeaver: I didn't know that, I thought it was $14

(1:39:43 / 1:43:32)Ridley Scott: 8.6

(1:39:44 /1:43:30)Sigourney: Aah, Wow!

(1:39:45 /1:43:32)Ridley Scott: Yeah, So at the end I said "I wanna spend X to give you a fourth act." "How much?And I said well, "it'll take us four days"... "Four Days!"I said "you really don't even know what I'm going to do yet," so I said, "let me explain to you what I'm going to do, then you'll go "how can you do that in four days?" as opposed to "four days!"(01:40:00). I said "we're not finishing the film when she jumps in the shuttle, there's a fourth act," And they said, "what do you mean, the film's over when she jumps in the shuttle and takes off and bingo!"I said "no, there's a fourth act in there that will change the way films are made" because
at at , I think until this moment, it's almost fair to say, there's
probably going to be some small independent film saying to me "you know, you're full of bull", but you know, today we've got an interesting idea of "now, the end, then the end and then the end, and by the way here's the other end",
right and I always wanted to close the lid and then suddenly let it out
again, babbam, okay. So when Ripley goes into that shuttle, there's a
moment when you know that the film isn't over where.. when you're
sitting in the seat.(alien anthology/quadrilogy A;ien commentary)

a) Short Lifecycle
Ridley went along wth the idea that alien creature has a limited lifespan like that of the life cycle like that of a butterfly or an insect. He wanted it to have a sort of timelessness. The thing that came out of the egg, the Face Hugger which was also known the "perambulatory penis", is the father. It is an abstract entity, in a sense, because all it does is plant a seed, and once having conceived, it dies.
Once it jumps out of the egg, it has to reproduce and spread as fast as possible, maybe in a cycle of perhaps only four days

b)Genetic traits
The alien creature lived to reproduce and so what the next generation would be doing would reflect that.

Once the derelict and the silo had been merged together the scenario was that a Space Jockey was infected and the
spores in the basement of the derelict were what became of the other
crew of the derelict.

However perhaps the idea of what the alien life form was doing as a concept was still evolving. One concept that Ridley talked about was that the next generation that followed the Face Hugger was the result was a combination of the original creature
and whatever host it uses.

Ridley also talked about how the next generation took on the characteristics of its last inhabitant and its new host, so in effect, the creature known as Kane's son had the space jockey as a grandparent and took on some of its features. The host is in effect the mother even if it is a male

So in that way, if the Face Hugger had hit the cat, it would have been a hybrid of the Space Jockey and the cat, if it could have been a dog, there would be a dog version of the alien. If it impregnates a man, the you get a man version of an Alien. Eventually the idea became that the space jockey was the pilot of a vessel that had been carrying the spores in its hold since the start of the journey.

c) A further dimension to the beast
And so Gordon Carrol and Ridley talked about it many times, should they indicated that the alien has intelligence , perhaps even great intelligence. Was it just a sort of a time bomb or even just a war machine?

Perhaps it was another form of society adjusting itself like ants, and as Ridley understood, ants had no sense of beginning or end, which goes back to his idea about the alien having a sort of timelessness.

Perhaps they were just born, run around doing this thing like everybody else in the community and then dies, and Ridley thought that this may have been the alien, and if that is so, then the alien had no intelligence except pure intuition about survival.

But there was the added question of what would you have if you're given the fact that this creature that's making use of a man's brain capacity.

Ants

d) Getting on with its lifecycle
This idea helped explain why the Alien didn't attack Ripley in the Narcissus, when Ripley kills it, the idea was that it would have died anyway.

Like a chameleon, it had found a protective corner in that ship and was working itself in there to die. It has to be provoked to attack because it had to get on with its life cycle.

Slime emanated from its body as if it were sealing itself in again like a cocoon, and perhaps it was transforming into a chrysalis, it's physical volume would decrease and it would transform into an egg and hibernate again.

This might seem to be a strange direction of thought because when humans become spores, Ridley talked about them being eaten away by the alien young and so grows the spore.

Does this mean the alien becomes consumed by its own biology in a similar way?

Ridley Scott: The thing that I was always frustrated about
was the absence of sense of smell with the beast. It's a real element
with him, because his odor must have been incredibly powerful. I wanted a
sense of a timeless, slightly decaying creature that, maybe,
only has a limited life cycle of, maybe, four days like an insect.
The alien life form lived to reproduce and in reproducing took on the
characteristics of its last inhabitant and its new host. Thus the alien
on board the Nostromo had the characteristics of the space jockey on the
derelict and Kane. If the facehugger had hit the cat, it could have
been a hybrid of the space jockey and the cat. When Ripley blasts off
from the Nostromo with the alien aboard, it's dying which is why it
moves so slowly. She kills it, but it would have died soon anyway. It's
like a butterfly(Fantastic Films #12, "Alien from the inside out", An exclusive interview with the Director of Alien, Ridley Scott, part two by James Delson p30)

Ridley Scott:A way of explaining what had happened on the
derelict [spaceship] and what was now happening on the NOSTROMO. And I
think it provided some explanation for the Alien's killing spree --
like a butterfly or an insect, it has a limited lifespan in which to
reproduce itself. It also helped explain why it didn't attack Ripley in
the Narcissus. It's days were over. Like a chameleon, it had found a
protective corner in that ship and was working itself in there to die.("Creating an Alien Ambience", Alien : The Special Effects)

Ridley Scott: I want to show that the Alien has a limited life cycle, like a
butterfly. And within that period of time once it decides to expose
itself - to coin a phrase - once it jumps out of the egg, it has to
reproduce and spread fast as possible, maybe in a cycle of only days.
And so in the last sequence, you see slime emanating from the big
Alien's body because we're trying to convey that maybe he's sealing
himself in again, like a cocoon. Also, by that point, he has to be
provoked to attack, because he has to get on with his life cycle. (Book of Alien, by Scanlon and Gross)

Ridley Scott:So whatever it impregnated, it could have been a dog and you would have had a dog version of alien. Impregnated with a man you get a man version of Alien. Which therefore maybe is even more lethal particularly if you’re picking up on man’s brain capacity as well. Because we never could work out…Gordon Carrol and I talked about this many times, you know, should we indicate the alien has intelligence. Or great intelligence. Or is it just a time bomb, just a time bomb, is it just a war machine? You know,…are those eggs simply war machines or are they ways of…another form of society adjusting itself like ants really…ants have…I think ants have no sense of beginning or end. They just are born, run around doing this thing like everybody else in the community and die. And I think that may have been the alien. So maybe the alien had no intelligence except pure intuition about survival. Right? ( report from the interview with Ridley Scott carried out for the Alien Evolution documentary, 2001)

Ridley Scott:Je voulais qu’Alien possédât au plus haut point cette force sexuelle. A
un moment, dans le film, il apparaît si mince, si élégant, qu’il en
devient presque trop humain. Mais, c’est normal; si la substance de
l’œuf s’était répandue sur un chien, Alien aurait ressemblé à un chien.
Dans le cas présent, sa “mère“, c’est bien le personnage joué par John
Hurt, il est donc logique qu’il ressemble à un homme. Translation: I wanted that ALIEN possessed the highest point this sexual force. At one point in the film , it seems so slim, so elegant, that it becomes almost too human. But this is normal ; if the substance of the egg had spread on a dog , Alien would have looked like a dog. In this case , his "mother" , it is the character played by John Hurt, so it makes sense that he looks like a man (Telerama n1548 12 septembre 1979)

Ridley Scott: The thing that came out of the egg, - the "perambulatory penis", as we used to call it - is the father. It is an abstact entity, in a sense, because all it does is plant a seed. Once having conceived, it dies and the next generation takes on characteristics of whatever life form it landed on. It could have been a dog, in which case, the Alien would have taken on a dog form. The result is a combination of two elements, the original creature and whatever host it uses.(American Cinematographer, August 1979, p842)